It is easy to be puzzled by the language which wireless speaker makers utilize to express the performance of their models. I am going to clarify the meaning of one usually used parameter: “signal-to-noise ratio” in order to help you make an informed decision whilst buying a brand new a couple of cordless loudspeakers. Once you have selected a number of cordless loudspeakers, it’s time to explore some of the specifications in more detail in order to help you narrow down your search to one model. The signal-to-noise ratio is a fairly essential specification and describes how much noise or hiss the cordless loudspeaker creates. A way to do a straightforward check of the noise performance of a pair of wireless speakers is to short circuit the transmitter audio input and then to crank up the wireless loudspeaker to its utmost. Next listen to the speaker. The static which you hear is produced by the wireless loudspeaker itself. Ensure that the gain of each set of cordless speakers is set to the same level. Otherwise you will not be able to objectively evaluate the amount of hiss between several models. The general rule is: the lower the level of hiss which you hear the better the noise performance.
While looking at the cordless loudspeaker spec sheet, you want to look for a couple of cordless loudspeaker with a high signal-to-noise ratio figure which suggests that the wireless speakers output a small amount of noise. One of the reasons why cordless speakers create noise is the fact that they use components like transistors as well as resistors which by nature generate noise. The overall noise is dependent on how much noise every component generates. However, the location of those elements is also essential. Elements which are part of the loudspeaker built-in amplifier input stage will usually contribute most of the noise. The wireless transmission itself also will cause static which is most noticable with products which utilize FM transmission at 900 MHz. FM transmitters are quite prone to cordless interference which is why newer models typically employ digital audio broadcast. The signal-to-noise ratio of digital transmitters is independent from the distance of the wireless speakers from Amphony Inc.. It is determined by how the audio signal is sampled. In addition, the quality of components inside the transmitter will affect the signal-to-noise ratio. The majority of of latest wireless speaker use amps which are based on a digital switching topology. These amplifiers are called “class-D” or “class-T” amps. Switching amplifiers include a power stage which is constantly switched at a frequency of approximately 400 kHz. This switching frequency is also hiss that is part of the amplified signal. On the other hand, latest wireless loudspeakerspecs normally only consider the hiss between 20 Hz and 20 kHz.
The signal-to-noise ratio is measured by inputting a 1 kHz test signal 60 dB below the full scale and measuring the noise floor of the signal generated by the built-in amp. The volume of the wireless speaker is couple such that the full output wattage of the built-in amp can be realized. Subsequently the noise-floor energy is measured in the frequency range between 20 Hz and 20 kHz and compared with the full scale signal energy. Often you will discover the expression “dBA” or “a-weighted” in your cordless loudspeaker spec sheet. A weighting is a method of expressing the noise floor in a more subjective fashion. This method was developed with the knowledge that human hearing perceives noise at different frequencies differently. Human hearing is most sensitive to signals around 1 kHz. On the other hand, signals under 50 Hz and higher than 13 kHz are hardly noticed. An A-weighted signal-to-noise ratio weighs the noise floor in accordance to the human hearing and is generally higher than the unweighted signal-to-noise ratio.